Valve train noise for any Chevy should be barely audible if not having excess wear and properly adjusted.
If it has hyd lifters it should be inaudible.
A noisy valve train is wearing itself out quicker than normal as the click is the proof of harsh metal to metal contact.
Excessive clearance is the cause and may be the result of accumulated wear or improper adjustment.
The worst sudden result can be broken off valve head/stem caused by the valve dropping onto the seat instead of controlled closing.
Accelerated wear of all componants and valve seat receding are slower results.
To correct, smooth or replace worn surfaces like valve tip,pushrod tip,rocker pad where it contacts valve, rocker and shaft wear---then set the clearance properly.
